Inshore Palm Islands

The northern boundary of the Palm Island Inshore reporting zone extends east from the north-west bank of the Seaforth Channel mouth, just south of Hinchinbrook Island, to the offshore boundary and includes enclosed coastal, open coastal and mid-shelf waters.

The southern boundary of the Palm Island zone extends eastward from the southern boundary of the Herbert River Basin to just east of the Palm Island Group and runs north to the Wet Tropics NRM marine region boundary at the junction with the offshore waters boundary.

The major river discharging into the Palm Island zone is the Herbert River. Several sub-catchments, including the Seymour River, also discharge into the Palm Island inshore zone.

Water quality in the Palm Island zone is affected by plumes of sediments, nutrients and pesticides from rivers discharging directly into the zone but also from the plumes of southern rivers, particularly the Burdekin River the mouth of which is approximately 180 km to the south-east.

The area includes the Palm Island group located approximately 17 km east of the mainland. The Palm Island Group includes Orpheus Island, Pelorus Island, Fantome Island, Palm Island, and Havannah Island. These islands provide fringing shallow water environments that support coral reef ecosystems and reef seagrass meadows.

The overall grade for Palm Island zone remained ‘moderate’ in 2019-20 with the score increasing from 56 to 59. 

The diagram below shows the detailed results for each indicator by year. Click on the timeslider to see data from previous years.

Water quality

The water quality grade in 2019-20 for the Palm Island inshore zone improved from ‘moderate’ to ‘good’ and scored 65, increasing from 60 in 2018-19.

Water quality grades are based on water quality guideline trigger values established for the waters of the Great Barrier Reef Marine Park that, if exceeded, identify the need for management responses. The guidelines are not targets or assessments of pollutant loads entering the marine environment. The results are derived from in-situ water samples and water quality loggers at two inshore locations.

The water clarity score of 91 (‘very good’) improved from 80 (‘good’) in 2018-19. Water clarity is comprised of total suspended solids and turbidity, both graded ‘very good’.

Nutrients scored 37 (‘poor’) and improved from a score of 2 (‘very poor’) in 2018-19. Nutrients are comprised of oxidised nitrogen (NOx) graded ‘poor’, particulate nitrogen (PN) graded ‘very poor’ and particulate phosphorus (PP) graded ‘good’. In contrast to 2018-19, there were no strong seasonal and spatial patterns associated with river discharge and nutrient concentrations during the considerably drier conditions of 2019-20.

The chlorophyll a score in the Palm Island zone was 68 (‘good’) and increased slightly from 66 (‘good’) the previous year.

A pesticide score was not available due to the cessation of pesticide logger deployment in the Palm Island zone.

 

Coral

The overall coral grade in 2019-20 for the Palm Island inshore zone was 53 (‘moderate’). It has remained ‘moderate’ since 2014-15.

The coral grade is comprised of the density of juvenile hard corals score of 51 (‘moderate’), the macroalgae cover score of 55 (‘moderate’), the coral cover score of 43 (‘moderate’), the change in coral cover score of 50 (‘moderate’), and the coral community composition score of 66 (‘good’).

The decline of grade for coral change from ‘good’ to ‘moderate’ contrasted with improvements in the grades for macroalgae and cover from ‘poor’ to ‘moderate’.

The occurrences of higher sea surface temperatures during early 2020 resulted in thermal stress and coral bleaching at most reefs in the Palm Island zone. The exception was Palms East where temperature stress was lower, corals did not bleach and coral cover continued to improve.

More information on recent changes in coral indicators and the relationships with environmental conditions are provided in the latest Marine Monitoring Program inshore coral report.

 

Seagrass

There is no current seagrass monitoring undertaken in the Palm Island Zone and consequently there is no seagrass grade available for the Report Card in the Palm Island Zone. 

 

Fish

The fish index is currently under development and will be available in future report cards.

 

References

Thompson A, Costello P, Davidson J, Logan M, Greg Coleman (2019) Marine Monitoring Program. Annual Report for inshore coral reef monitoring: 2017 to 2018. Australian Institute of Marine Science, Townsville.132 pp. 

 

See the detailed reports for further information on the methods used to produce the scores and grades and the detailed results